On Mac, Android does not automatically allow you to transfer files. Unfortunately, you’ll need an extra program to transfer files from your Mac to Android devices. One of the programs that allows you to do this is called Android File Transfer.
1) Download Android File Transfer.
Hit the green Download Now button.
2) Open the downloaded androidfiletransfer.dmg
Drag and drop Android File Transfer into the Applications folder.
3) Open Android File Transfer.
At this point, Android File Transfer should be inside the Applications folder. Simply double click the application.
4) Connect your Android device to your computer.
Your Android device should be automatically detected. You can drag and drop files from your Mac to your Android device OR from your Android device to Mac. Simply highlight or hold CTRL and click on the files that you want to transfer. Drag and drop between devices.